Methanogen

About: Methanogen is a research topic. Over the lifetime, 1146 publications have been published within this topic receiving 48254 citations.

Effect of dilution rate on the microbial structure of a mesophilic butyrate-degrading methanogenic community during continuous cultivation.

Abstract: We constructed two mesophilic anaerobic chemostats that were continuously fed with synthetic wastewater containing butyrate as the sole source of carbon and energy. Steady-state conditions were achieved at dilution rates between 0.025 and 0.7 day−1. Butyrate, fed into the chemostat, was almost completely mineralized to CH4 and CO2 at dilution rates below 0.5 day−1. The butyrate-degrading methanogenic communities in the chemostats at dilution rates between 0.025 and 0.7 day−1 were monitored based on the 16S rRNA gene, using molecular biological techniques including clone library analysis, denaturing gradient gel electrophoresis, and quantitative real-time polymerase chain reaction. The aceticlastic methanogen Methanosaeta and the hydrogenotrophic methanogen Methanoculleus dominated in methanogens at low dilution rates, whereas the aceticlastic methanogen Methanosaeta, Methanosarcina, the hydrogenotrophic methanogen Methanoculleus, and Methanospirillum dominated at high dilution rates. Bacteria affiliated with the family Syntrophaceae in the phylum Proteobacteria predominated at the low dilution rate of 0.025 day−1, whereas bacteria affiliated with the phylum Firmicutes and Candidate division OP3 predominated at high dilution rates. A significant quantity of bacteria closely related to the genus Syntrophomonas was detected at high dilution rates. Dilution rate showed an apparent effect on archaeal and bacterial communities in the butyrate-fed chemostats.

A New Combination of Substrates: Biogas Production and Diversity of the Methanogenic Microorganisms.

Abstract: Agriculture, food industry, and manufacturing are just some of the areas where anaerobic technology can be used. Currently, anaerobic technologies are mainly used for wastewater treatment, solid waste treatment, or for the production of electrical and thermal energy from energy crops processing. However, a clear trend is towards more intensive use of this technology in biomass and biodegradable waste processing and hydrogen or biomethane production. An enormous number of anaerobic digesters are operating worldwide but there is very little information about the effect of different substrate combinations on the methanogens community. This is due to the fact that each of the anaerobic digesters has its own unique microbial community. For the most effective management of anaerobic processes it would be important to know the composition of a consortium of anaerobic microorganisms present in anaerobic digesters processing different input combinations of raw material. This paper characterizes the effect of the input raw materials on the diversity of the methanogen community. Two predominant microorganisms in anaerobic digesters were found to be 99% identity by the sequences of the 16S rRNA gene to the Methanoculleus and Thermogymnomonas genera deposited in GenBank.

Biostimulation of anaerobic BTEX biodegradation under fermentative methanogenic conditions at source-zone groundwater contaminated with a biodiesel blend (B20)

Abstract: Field experiments were conducted to assess the potential for anaerobic biostimulation to enhance BTEX biodegradation under fermentative methanogen- ic conditions in groundwater impacted by a biodiesel blend (B20, consisting of 20 % v/v biodiesel and 80 % v/v diesel). B20 (100 L) was released at each of two plots through an area of 1 m 2 that was excavated down to the water table, 1.6 m below ground surface. One release was biostimulated with ammonium acetate, which was added weekly through injection wells near the source zone over 15 months. The other release was not biostimulated and served as a baseline control simulat- ing natural attenuation. Ammonium acetate addition stimulated the development of strongly anaerobic conditions, as indicated by near-saturation methane concentrations. BTEX removal began within 8 months in the biostimulated source zone, but not in the natural attenuation control, where BTEX concentrations were still increasing (due to source dissolution) 2 years after the release. Phylogenetic analysis using quantitative PCR indicated an increase in concentration and relative abundance of Archaea (Crenarchaeota and Eur- yarchaeota), Geobacteraceae (Geobacter and Pelob- acter spp.) and sulfate-reducing bacteria (Desulfovibrio, Desulfomicrobium, Desulfuromusa ,a ndDesulfuromon- as) in the biostimulated plot relative to the control. Apparently, biostimulation fortuitously enhanced the growth of putative anaerobic BTEX degraders and associated commensal microorganisms that consume acetate and H2, and enhance the thermodynamic feasi- bility of BTEX fermentation. This is the first field study to suggest that anaerobic-methanogenic biostimulation could enhance source zone bioremediation of ground- water aquifers impacted by biodiesel blends.